Current Meter Research Articles

Analysis of Upwelling Events in the Southern South China Sea Using Multi-Mission Satellite Altimeter

Upwelling is a vital ocean behaviour, especially for the Fisheries Industry, where upwelling will help to detect fish ground at a particular ocean area. However, the study of upwelling is minimal and not well understood due to some reasons and constraints, such as limited observation. Upwelling lacks a comprehensive in-situ observation system where it relies on limited information collected from the ground-truthing execution such as ships, buoys, and current meter. This study aims to analyse the upwelling pattern in the southern region of the South China Sea by using a multi-mission satellite altimeter. In order to derive the physical oceanography that involves upwelling, such as sea surface height (SSH), Mean Dynamic Topography (MDT), and the Sea Level Anomaly (SLA), the Radar Altimeter Database System is used. Five Satellite Altimeter mission is used in this study, which is JASON-2, JASON-3, CYROSAT2, SARAL, SENTINAL3A from 2013 to 2017. Validation is made using a statistical method showing a good correlation between Altimetry data and Tidal Data at tide gauge, which is 0.84 to 0.97, respectively. Also, monthly altimetry derived Geostrophic Current was assessed by analysing the current pattern where it shows a similarity with a previous study where the current velocity is 0.5ms-1 to 2ms-1. From the result, eddies can be seen in the seasonal and monthly Absolute Geostrophic Ocean Current (AGOC) map, indicating the present presence of upwelling. In conclusion, this study will benefit other researchers in terms of both upwelling and eddy studies.

Summertime M2 Internal Tides in the Northern Yellow Sea

The summertime M2 internal tide in the northern Yellow Sea is investigated with moored current meter observations and numerical current model results. The hydrodynamic model, which is implemented from the Regional Ocean Model System (ROMS) with 1 km horizontal resolution, is capable of resolving the internal tidal dynamics and the results are validated in a comparison with observations. The vertical pattern of a mode-1, semi-diurnal internal tide is clearly captured by the moored ADCP as well as in the simulation results. Spectral analysis of the current results shows that the M2 internal tide is dominant in the northern Yellow Sea. Analysis of the major M2 internal tide energetics demonstrated a complex spatial pattern. The tidal mixing front along the Korean coast and on the northern shelf provided proper conditions for the generation and propagation of the internal tides. Near the Changshan islands, the M2 internal tide is mainly generated near the local topography anomalies with relatively strong current magnitude, equal to about 30% of the barotropic component, thus modifying the local current field. These local internal tides are short-lived phenomena rapidly being dissipated along the propagation pathway, restricting their influence within a few kilometers around the islands.

Unsteady turbulent flow developing inside and around different parts of fluttering trawl net in flume tank

Fluttering motions of a trawl are affected by its geometrical shape, natural underwater flows, and unsteady turbulent flow inside and around it. Thus, knowledge of the interaction between fluttering motions and the turbulent flow developing inside and around the different parts of the trawl is essential for understanding the hydrodynamic performance and selectivity of fishing gear. This paper assesses the coupled dynamics of the fluttering motions of different parts of a trawl and their hydrodynamics behavior. The analysis is based on three-dimensional electromagnetic current velocity meter measurements carried out inside and around different parts of a 1/18 scaled bottom trawl model. Instantaneous flow velocity fields and turbulent flow parameters were analyzed from obtained flow data. Moreover, fast Fourier transform and wavelet transform analysis were conducted to analyze the time–frequency contents of instantaneous flow velocity fields and fluctuating parts. The motions of different parts of the trawl net were oscillatory quasi-periodic and related to low frequency activity. The mean velocity ratios inside and around trawl wing, square, trawl body, and codend were 0.92, 0.89, 0.86, and 0.84, respectively. These results demonstrate the existence of unsteady turbulent flow inside and around different parts of the trawl. This unsteady turbulent flow corresponds to turbulent boundary layer flow, turbulent flow because of trawl wake, and vortex shedding. The dominant frequencies of these unsteady turbulent flows showed low frequency activities and wavelet energy was transferred from small-scale to large-scale motions under unsteady shear turbulence. In addition, knowledge of unsteady turbulent flow is greatly important for better understanding the hydrodynamic forces acting on a trawl and its geometrical shape as well as for implementing various selective devices and mesh shapes to reduce juvenile by-catch.

Moored Observations of Currents and Water Mass Properties between Talaud and Halmahera Islands at the Entrance of the Indonesian Seas

AbstractThe currents and water mass properties at the Pacific entrance of the Indonesian seas are studied using measurements of three subsurface moorings deployed between the Talaud and Halmahera Islands. The moored current meter data show northeastward mean currents toward the Pacific Ocean in the upper 400 m during the nearly 2-yr mooring period, with the maximum velocity in the northern part of the channel. The mean transport between 60- and 300-m depths is estimated to be 10.1–13.2 Sv (1 Sv ≡ 106 m3 s−1) during 2016–17, when all three moorings have measurements. The variability of the along-channel velocity is dominated by low-frequency signals (periods > 150 days), with northeastward variations in boreal winter and southwestward variations in summer in the superposition of the annual and semiannual harmonics. The current variations evidence the seasonal movement of the Mindanao Current retroflection, which is supported by satellite sea level and ocean color data, showing a cyclonic intrusion into the northern Maluku Sea in boreal winter whereas a leaping path occurs north of the Talaud Islands in summer. During Apri–July, the moored CTDs near 200 m show southwestward currents carrying the salty South Pacific Tropical Water into the Maluku Sea.

A blockchain‐enabled secured fault allocation in smart grids based on μ PMUs and UT

Improvements in the high accuracy of micro-phasor measurement unit (μPMU) and synchrophasor unit provide the distribution network a special perspective to access full observability in the presence of renewable distribution generations (DGs). In this regard, modelling the uncertainty effects for accurate fault detection in smart grids has become a novel turning point. This research work attempts to develop a novel stochastic architecture based on unscented transform (UT), which requires a very few number of μPMUs, to communicate in a secured blockchain-enabled structure to allocate and detect the smart grid irregularities and faults. Such a blockchain-based technique can be beneficial for encrypting the data transmitted among the μPMUs in the smart grid consisting of a variety of distributed energy sources (DERs) and high impedance fault events, while incorporating the uncertainties associated with the load and individual installation sensors. The proposed stochastic structure benefits from voltage measurement and uses its angle in event placement that performs more efficiently than the conventional sensors based on high-voltage and current metering. The simulation results show the great precision and effectiveness of the proposed model during various fault scenarios in smart grid.

Natural vs. trawling-induced water turbidity and suspended sediment transport variability within the Palamós Canyon (NW Mediterranean)

Increases of water turbidity and suspended sediment transport in submarine canyons have been associated with high-energy events such as storms, river floods and dense shelf water cascading (DSWC), and occasionally with bottom trawling along canyon flanks and rims. To assess the variations on the water column turbidity and sediment transport in the Palamós Canyon linked to both natural and trawling-induced processes, an autonomous hydrographic profiler, as well as a near-bottom current meter and a turbidimeter were deployed in the canyon axis (929 m depth) from February to June 2017, covering a trawling closure (February) and trawling activities (March-June). Periods of enhanced water turbidity during the trawling closure were mostly associated with storms and DSWC events, transporting turbid dense waters into the canyon. In absence of such events, the water column displayed low suspended sediment concentrations (~ 0.3 mg L− 1) until the trawling season began, when particulate matter detachments, ranging between > 1 mg L− 1 and 3.8 mg L− 1, were observed at the water depths where the trawling grounds are found. During the trawling closure, high near-bottom suspended sediment fluxes (35–44 g m− 2 s− 1) were sporadically registered at ~ 920 m depth associated with a major storm and DSWC event. Smaller but more frequent increases of near-bottom suspended sediment fluxes (0.1–1.4 g m− 2 s− 1) were recorded during trawling activities. Despite these smaller trawling-induced suspended sediment fluxes, 30 days of continuous bottom trawling activity transported a total amount of 40 kg m− 2, of similar magnitude to that generated by a major DSWC event (50 kg m− 2). Since bottom trawling in Palamós Canyon is practiced on a daily basis throughout the year, a much larger contribution of anthropogenically derived water turbidity and suspended sediment transport can be expected.

Development and validation of a low-cost direct current resistivity meter for humanitarian geophysics applications

Insufficient access to safe drinking water is one of the most challenging global humanitarian issues. The development of low-cost microcontrollers and the widespread availability of cheap electronic components raise the possibility of developing and using low-cost geophysical instrumentation with open-source designs and software solutions to circumvent geophysical instrumentation capital cost issues. To these ends, we alter an existing low-cost direct current (DC) resistivity meter design and develop an optional modular Raspberry Pi data-logging system to improve the unit’s functionality and usability and to ensure data integrity. Numerical modeling and physical testing demonstrate that the system is more robust than previously published low-cost designs and works in a more diverse range of geologic scenarios — especially conductive environments. Our instrument was tested in a Geoscientists Without Borders project jointly run between researchers from Colorado School of Mines (CSM) and Université d’Abomey-Calavi (UAC), Cotonou, Benin. A key project component involved CSM and UAC students constructing and validating two low-cost DC resistivity meters and then using these instruments for fieldwork aimed at better characterizing and monitoring the health of a local aquifer used as a groundwater source for communities in the Cotonou region. The low-cost instruments were successfully used alongside a commercial resistivity meter to acquire data for 2D inversion of aquifer hydrostratigraphy, indicating the presence of a clay-sand contact. The costs of the redesigned instrument and data logger, respectively, are $177 and $108 (in 2021 USD) with future cost reductions possible, which are fractions of the price of commercial resistivity meters.

Model tests and full-scale sea trials for drag force and deformation of a marine aquaculture net cage

In this study, we investigated the hydrodynamic characteristics of marine aquaculture net cages used for farming silver salmon (Oncorhynchus kisutch). Two sets of experiments were conducted: model-scale testing, which was used to measure the drag force and deformation of a model net cage at different current velocities, and full-scale testing, which involved a sea trial at a silver salmon farm site. In the sea trial, an acoustic wave and current meter was deployed to record the current velocities around the net cage, and the cage deformation was estimated from the several vertical positions of net using 13 depth sensors. The precision of estimating the cage deformation using only the depth information was evaluated by comparing the estimated cage deformation with that determined from the images in model-scale testing. Comparing the model-scale and full-scale testing results showed that only the bottom netting was found to be deformed under lower water currents. The trends observed for the drag force, cage deformation, and cross-section area estimated from the depth data in full-scale testing were generally consistent with those converted from the model-scale testing using Tauti's similarity law. However, the drag force values of a full-scale net cage converted from the model-scale testing were higher than those estimated from the depth data in the full-scale testing. In contrast, the converted cross-sectional areas from model-scale testing were smaller than the estimated values in full-scale testing. In future, the cage deformation should be examined under higher current velocities, and the drag force should be measured in the full-scale testing to validate the results of the model-scale testing and the hydrodynamic model.

Origin of Sustained Continuous Measurements of Surface Wind and Upper-Ocean Current and Temperature on the Pacific Equator: EQUA Project

AbstractIn 1976, a pilot experiment, called first Equatorial Mooring (EQUA-1), tested an innovative technique for anchoring a taut-line surface mooring at 0°, 150°W where the water depth is 4.5 km. The 36-day deployment contained a wind recorder and fixed-level current meters at 50 and 100 m in the Equatorial Undercurrent (EUC). The following year, in a second pilot experiment, named EQUA-2, a similar mooring was deployed at 0°, 125°W for 99 days. EQUA-2, with current meters at 10, 50, 100, 150, and 200 m, recorded a surge in EUC transport during April 1977 when 3-day-averaged eastward current speeds at 50-m depth reached 2 m s−1. The associated eastward transport per unit meridional width over the 50–200-m layer was 190 m2 s−1. Based on observations recorded in April 1980, the EQUA-2 pulse would correspond to a total EUC transport surge of about 38 Sv (1 Sv ≡ 106 m3 s−1) and would represent an equatorially trapped first-mode baroclinic Kelvin wave. This paper describes EQUA Project observations and why and how I created the high-risk-of-failure opportunity to record pioneering time series measurements at the equator. The enduring legacy of the EQUA Project is the sustained maintenance of in situ surface wind and upper-ocean current and temperature measurements at numerous sites in the equatorial oceans, starting in the Pacific to improve forecasts of the El Niño and La Niña phenomenon. For example, the 40-yr records of surface wind and upper-ocean current and temperature measurements at 0°, 110°W and 0°, 140°W are some of oceanography’s longest time series recorded far from land.

The 2019 Brazilian oil spill: Insights on the physics behind the drift

This study uses global numerical model results of ocean and atmospheric circulation, as well as local wind, wave and current meter data, to investigate the structure of the ocean and coastal circulation potentially associated with the transport of oil that affected thousands of kilometers of the Brazilian coast in 2019. Our analysis suggests the oil was brought close to the continental shelf sometime in August 2019 by the southern branch of South Equatorial Current, and was initially advected towards the north by the North Brazilian Current and shelf currents pushed by SE winds. The onset of negative along-shore winds close to the coast in September–October 2019 turned the coastal along-shore drift south, a situation that persisted throughout the spring and summer seasons. Along the east coast, where observational data was available, landward cross-shelf flows below 17 m of depth, associated with coastal upwelling conditions, advected the oil from the slope onto the outer and mid-shelf. On the inner-shelf the oil was finally pushed towards the beaches by the wave action close to the bottom. Reports of oil arriving on the east coast followed changes in coastal wind and current patterns very closely. It is suggested that before reaching the shelf, the oil drifted at depths larger than 17 m, perhaps reaching several tens of meters.

Bathymetric components towards ensuring navigable channel along a section of lower river Niger, lokoja, kogi state, Nigeria

Navigation in Lower River Niger is seasonal because of insufficient water depth during the dry season. This is a limitation to economic benefits derivable compared to when the river is navigable throughout the year. Government and stakeholders alike have exerted efforts in the past years to create an unimpeded navigable channel without much success. The need to ensure all-year-round navigation in the Lower River Niger for industrial and commercial purposes necessitated this research work. The main thrust of this work is to determine bathymetric components parameters of the river necessary for the design of an appropriate river training structure to divert river flow from the secondary channel to the main channel. The specific objective hereto is to assess the extent and geometry of the river banks, the configuration of the river bed, the river flow velocity and discharge. The approach deployed in this work is the classical method of acoustic principle premised on Remote Sensing techniques. The shape of the river was obtained through waypoint survey using Garmin eTrex 10 handheld GPS, while the riverbed configuration was determined through bathymetric survey using Odom Echotrack MK III single beam Echo Sounder and the flow velocity data was acquired using Valeport 106 Current Meter. Data processing and analysis were achieved using Garmin Basecamp 4.7.3, Wintopo V7.03, Valeport Datalog X2 and Surfer 13 software. The length of the study area measured along the main channel was obtained as 5.94km while that of secondary channel gave 4.30km. Area occupied by the main channel was found to be 2,636,331.3m2 and 1,759,045.4m2 for the secondary channel. Average depth on the main channel was 0.21m while on the secondary channel was -0.89m, depth figures referred to Lokoja local datum. The average flow velocity was obtained to be 0.449m/s and the cross-sectional area of the river as 1568.75m2, which gave a value of 704.2m3/s for the river discharge. The research produced the digital terrain model (DTM) and bathymetric charts of the study area. The parameters obtained in this study is a useful tool in defining an appropriate embankment dam suitable to divert the flow from the secondary channel to the main channel to enhance depth towards all-season navigation in Lower River Niger.

Australian tidal currents – assessment of a barotropic model (COMPAS v1.3.0 rev6631) with an unstructured grid

Abstract. While the variations of tidal range are large and fairly well known across Australia (less than 1 m near Perth but more than 14 m in King Sound), the properties of the tidal currents are not. We describe a new regional model of Australian tides and assess it against a validation dataset comprising tidal height and velocity constituents at 615 tide gauge sites and 95 current meter sites. The model is a barotropic implementation of COMPAS, an unstructured-grid primitive-equation model that is forced at the open boundaries by TPXO9v1. The mean absolute error (MAE) of the modelled M2 height amplitude is 8.8 cm, or 12 % of the 73 cm mean observed amplitude. The MAE of phase (10∘), however, is significant, so the M2 mean magnitude of vector error (MMVE, 18.2 cm) is significantly greater. The root sum square over the eight major constituents is 26 % of the observed amplitude. We conclude that while the model has skill at height in all regions, there is definitely room for improvement (especially at some specific locations). For the M2 major axis velocity amplitude, the MAE across the 95 current meter sites, where the observed amplitude ranges from 0.1 to 156 cm s−1, is 6.9 cm s−1, or 22 % of the 31.7 cm s−1 observed mean. This nationwide average result is encouraging, but it conceals a very large regional variation. Relative errors of the tidal current amplitudes on the narrow shelves of New South Wales (NSW) and Western Australia exceed 100 %, but tidal currents are weak and negligible there compared to non-tidal currents, so the tidal errors are of little practical significance. Looking nationwide, we show that the model has predictive value for much of the 79 % of Australia's shelf seas where tides are a major component of the total velocity variability. In descending order this includes the Bass Strait, the Kimberley to Arnhem Land, and southern Great Barrier Reef regions. There is limited observational evidence to confirm that the model is also valuable for currents in other regions across northern Australia. We plan to commence publishing “unofficial” tidal current predictions for chosen regions in the near future based on both our COMPAS model and the validation dataset we have assembled.

Variability and Sources of the Internal Wave Continuum Examined from Global Moored Velocity Records

AbstractEnergy for ocean turbulence is thought to be transferred from its presumed sources (viz., the mesoscale eddy field, near-inertial internal waves, and internal tides) to the internal wave continuum, and through the continuum via resonant triad interactions to breaking scales. To test these ideas, the level and variability of the oceanic internal gravity wave continuum spectrum are examined by computing time-dependent rotary spectra from a global database of 2260 current meter records deployed on 1362 separate moorings. Time series of energy in the continuum and the three “source bands” (near-inertial, tidal, and mesoscale) are computed, and their variability and covariability examined. Seasonal modulation of the continuum by factors of up to 5 is seen in the upper ocean, implicating wind-driven near-inertial waves as an important source. The time series of the continuum is found to correlate more strongly with the near-inertial peak than with the semidiurnal or mesoscale. The use of moored internal-wave kinetic energy frequency spectra as an alternate input to the traditional shear or strain wavenumber spectra in the Gregg–Henyey–Polzin finescale parameterization is explored and compared to traditional strain-based estimates.

Tekhnicheskiye sredstva i metodika issledovaniya tonkoy struktury techeniya vodnogo potoka s ispol'zovaniyem videoregistratsii

The article discusses developed technical means and methods allowing to obtain in situ spatial distribution of velocity of suspended particle movement by a water flow. A brief description is given of the developed measuring complex based on video recording of the aquatic environment. The method of performing full-scale experiments by the example of study of sea estuaries is described. The article presents measurement results and examples of spatial distributions of flow velocities required for solving various problems related to mass transfer, coast erosion and silting of water areas. Analysis of expedition research results obtained using the developed complex allowed to create methodical approaches to assess the current state of a water body and informative parameters of its state using a visualization method. Based on the created methods, data on the fine structure of the flow in the Chernaya River estuary area were obtained. Comparison of the averaged data on the water flow velocity with the measurement results obtained through standard technical means, namely a hydrometric current meter, showed minimal discrepancies not exceeding 11 %. The developed method and technical means make it possible to study the water flow dynamics and to describe the flow fine structure, which is necessary for studying the mechanisms of erosion, sediment accumulation and transport.

Wave Transformation on a Fringing Reef System With Spur and Groove Structures

AbstractSpurs and Grooves (SAG) are coral forereef structures with their main axis normal to the reef crest. The dimensions of SAG vary considerably on a global scale. Despite being common, there are relatively few studies that relate SAG morphology with wave transformation processes. Measurements of wave transformation are presented from Xahuayxol, Quintana Roo, Mexico, across a SAG zone with larger spurs than in previous studies. An array of pressure sensors and current meters sampling at high frequencies were deployed over 8 days. Our results show that SAG structures are more important for wave transformation than previously reported since a high rate of wave energy flux dissipation (up to 0.077 kW/m2) was found and the corresponding wave dissipation friction factor, fw (1.01), was four times higher as compared to other reefs. We also found that the wave dissipation rate over the spurs can be up to three times higher than the adjacent grooves (0.098 vs. 0.028 kW/m2). This study demonstrates that SAG plays a very important role in wave dissipation over coral reefs.

The Effects of Tidal Translation on Wave and Current Dynamics on a Barred Macrotidal Beach, Northern France

Barred macrotidal beaches are affected by continuous horizontal displacements of different hydrodynamic zones associated with wave transformation (shoaling, breaker and surf zones) due to significant tide-induced water level changes. A series of wave and current meters, complemented by a video imagery system, were deployed on a barred beach of northern France during a 6-day experiment in order to characterize the spatial and temporal variability of wave-induced processes across the beach. Wave and current spectral analyses and analyses of cross-shore current direction and asymmetry resulted in the identification of distinct hydrodynamic processes, including the development of infragravity waves and offshore-directed flows in the breaker and surf zones. Our results revealed a high spatial variability in the hydrodynamic processes across the beach, related to the bar-trough topography, as well as significant variations in the directions and intensity of cross-shore currents at fixed locations due to the horizontal translation of the different hydrodynamic zones resulting from continuous changes in water level due to tides.

Blending drifters and altimetric data to estimate surface currents: Application in the Levantine Mediterranean and objective validation with different data types

An improved estimation of the surface currents in the Levantine Basin of the Mediterranean sea is crucial for a wide range of applications, including pollutants transport and nutrients distribution. This estimation remains challenging due to the scarcity or shortcomings of various data types used for this purpose. In this paper, we present an objective validation of a variational assimilation algorithm that blends geostrophic velocities derived from altimetry, wind-induced velocities, and drifter positions, to continuously obtain velocity corrections. The assessment of the validation impact was based on available independent in-situ data (current meters, gliders, and independent drifters) and satellite ocean color images. In all cases, the improvement was shown either qualitatively (position of the eddies) or quantitatively.

Moored Observations of the Iceland‐Scotland Overflow Plume Along the Eastern Flank of the Reykjanes Ridge

AbstractSince 2014, an array of current meters deployed in the Iceland Basin as part of the Overturning in the Subpolar North Atlantic Program has provided new measurements of the southward flow of Iceland‐Scotland Overflow Water (ISOW) along the eastern flank of the Reykjanes Ridge. The location of the array, near 58–59°N, captures the ISOW plume at the farthest downstream location in the Iceland Basin before significant amounts of ISOW can flow into the Irminger Basin through deep fractures in the Reykjanes Ridge. The net transport of the ISOW plume at this location—approximately 5.3 Sv based on the first 4 years of observations—is significantly larger than previous values obtained farther north in the Iceland Basin, suggesting that either previous measurements did not fully capture the plume transport or that additional entrainment into the ISOW plume occurs as it approaches the southern tip of the Reykjanes Ridge. A detailed water mass analysis of the plume from continuous temperature/salinity observations shows that about 50% of the plume transport (2.6 Sv) is derived from dense waters flowing over the Nordic Sea sills into the Iceland Basin, while the remainder is made up of nearly equal parts of entrained Atlantic thermocline water and modified Labrador Sea Water. The overall results from this study suggest that the ISOW plume approximately doubles its transport through entrainment, similar to that of the Denmark Strait overflow plume in the Irminger Sea that forms the other major overflow source of North Atlantic Deep Water.

Structure from Motion (SfM) method to characterize fluvial sedimentology in Way Semaka river in Lampung province, Indonesia

Structure from motion (SfM) has been applied recently in fluvial sedimentology. This application is due to the availability of many low-cost unmanned aerial vehicles/drones, which can help overcome challenging terrain, provide efficient and reproducible and high-accuracy topographic images and data. The current study describes the application of SfM to build a geomorphological model and estimate the surface water velocity of the Way Semaka River in the Bandar Negeri Suoh (BNS) region in the West Lampung area. Way Semaka is a river type with an extensive meandering system and stable extension tectonic regime relatively. River morphology approximately 96.62 m width and 4 m depth in straight (relatively) area, whereas in channel area approximately 171.22 m width and 5 m depth. The velocity range between 0.39 – 1.56 m/s based on image analysis proven by current meter measurements onsite with an RMS error of 0.25. Manual geomorphic unit level 2 analysis revealed that 9% of the coverage consisted of basins for the channel’s zone, 35% of the coverage consisted of convexity, 9% consisted of planar features, and 37% of the coverage consisted of the transition zone.

Analysis of daily dynamics of thermal interaction of temperature and ocean flow in seaweed growth areas

Seaweed (Caulerpa sp) is a marine biota whose growth is influenced by physical parameters. The purpose of this study was to analyze the dynamics of daily temporal changes in seawater temperature at several depth points and variations in the velocity and direction of ocean currents. Make simple mathematical modeling of ocean current velocity and daily dynamics of seawater temperature in the seaweed growth zone and outside the seaweed growth area. Temperature measurements are carried out on 4 depth variations using a current meter when the sun illuminates the ocean. Measurement of the velocity and direction of the current is carried out using a current measuring instrument during the full moon. The Fourier function or periodic function determines mathematical modeling. The results showed that the transect measurement of sea temperature for 4 depth variations experienced changes due to the intensity of solar irradiation. During one cycle, the speed and direction of the ocean currents change periodically, with the average flow velocity in the seaweed zone being 7.4 m/min and outside the Lahe region being 18.75 m/min directly to the southwest at seawater flows at high tide and northeast experiencing low tide. The daily temporal change in ocean current velocity for each measurement transect shows the same shape which is modeled according to the Fourier function.